Vacuum drying is mainly carried out in low vacuum area. In the process of grain moisture vaporization, its boiling evaporation temperature is proportional to the ambient pressure. The high moisture grain is placed in a sealed drying cylinder to form and maintain a certain degree of vacuum. At the same time, the grain in the drying cylinder is heated continuously, so that the moisture in the grain diffuses to the surface through the pressure difference. After vaporization, it is pumped out by a vacuum pump to realize continuous pairing in vacuum and low temperature. High moisture grain is dehydrated and dried. Vacuum drying reduces the boiling evaporation temperature of water from 100 C to below 40 C. Because the evaporation temperature is lower than the gelatinization temperature of starch, the grain will not be damaged. It avoids the expansion of grain and bursting waist, and ensures the quality of grain after drying. It guarantees that the original color, aroma, taste, nutrient composition and quality of the material are basically unchanged after drying. It is a real low-temperature drying, which is completely different from the general hot air low-temperature drying.roots-vacuum-pump-in-condenser
Vacuum freeze drying technology is to freeze the material first, then heat up under vacuum conditions, so that ice sublimation can achieve the purpose of post-drying. The heating methods adopted include infrared heating and microwave heating. The heat provided should not only sublimate the ice quickly but also damage the surface of the product. Vacuum freeze-drying technology can keep food fresh by vacuum atmosphere in the past 20 years. The packaging technology has developed rapidly. Because this kind of packaging not only has the characteristics of free oxygen to make food not easy to decay and deteriorate, fitted and inflatable packaging can not be harmed by insects and can inhibit the growth of mould, can improve and prolong the degree of food preservation and storage time, but also has the advantages of simple structure, easy operation, low price, low cost, elegant appearance and easy popularization of plastic packaging materials. There are many kinds of food in vacuum packaging, such as mustard pickles, turnips, kelp, sausage, grilled chicken, roast duck, soybean products, milk powder, wheat milk essence and so on. Because fresh products go through a long period of time from harvesting to reselling, it is easy to increase the selling price because of the serious loss. The promotion of vacuum packaging technology will reduce the price and refrigeration cost of fresh products, thus alleviating the spearhead between supply and demand. Therefore, vacuum preservation will become a potential market and be active in people's lives.rotary_vane_vacuum_pump
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